The Stovebolt Site Forums The Shop Area Engine Shop Need help with my Carb....please

I am finally putting on the finishing touches to my 270 and I started cleaning up the carburetor that was on it when I bought it. This carburetor is not listed in my maintenance manual and I was hoping to clean/rebuild it. Anyway, it is not the standard Zenith up or downdraft and it is not one of the Holleys. It has a stamp of CARTER YF on one side. Other than that there is nothing that directly tells me what it is.

Is this an appropriate carb for a standard 270? If not, would the zenith downdraft be a better solution than one of the Holleys? I appreciate any oppinions on what carb would be the most appropriate for a standard 270, not a hotrod.

Thanks,

Tom

I had a Rochester "B" downdraft from a 235 Chev. on my 248; worked well. I don't know what happened to the stock Zenith carb, but I am not impressed with them anyway. Just Do Not overtighten the four screws that hold down the air horn on the "Rotten-Chester". They are famous for leaking here.

Carter carbs are almost always found on old F O R D 's and some Mopar's. Also, Studebaker used Carter carbs.

I like the Zenith on my 248; no horsepower to speak of, but you can't find a flatter torque curve. I don't know if the Zenith downdraft was standard on the 270, but I believe the updraft carbs were used on COE and big rigs only... :confused: I'm sure someone will jump on this with a correction. :p

Keep the YF, it is a good carb and is appropriate. They don't leak like the rochesters and rebuild kits are cheap. They were also used on Willys engines of the era.

The Carter YF design is one of the finest single barrels in existance (my opinion); however they have been used on engines from about 130 to 300 cubic inch displacement. These differ internally as to venturi size. Chances are good that the one you have is probably a replacement unit for a Chevrolet, and is marginally large enough for the 270.

Most of the YF Carters have a STAMPED number followed by the letter "S" on the bowl (center section) of the unit. A common example would be a 967S (Chevy replacement). If you can find this number, we can determine applicability to the 270. None of the raised numbers on the unit have any meaning. The stamped (or recessed) number followed by the letter "S" is the only identification number.

Jon.

Thanks for the information, and I really appreciate carbking's conviction for the Carter.

Couple of questions about the Y-F:
What is included in the rebuild?
Where can I get a detailed, part-by-part manual on repairing/rebuilding the Y-F?
I read it can supply 250 CFM...is that correct and is that enough/too much for the 270?

Thanks again for the help and I hope to put your answers to good use.

Tom

What do you get in a rebuild kit? depends you can get a gasket kit (gaskets only) or you can get a full kit which has float seat/needle, accelletor pump, may contain ventures and hi speed needles. if you can find the brass tag # and let me know i do have the Carter Carb book and send you the scans of the rebuild procedure and the parts for it, as well as find out what motor it was intended for..

Here is a link that was put on here some time ago:

Carter YF carb manual

As previously stated, I really like the YF design. The only thing I don't like about it is the pump diaphragm (leather accelerator pumps are much more trouble-free).

The key to using a YF carburetor is to use the RIGHT YF carburetor. Carter made literally hundreds of different versions of the YF. Too large a carburetor will run rich at idle, lean at cruise, and be sluggish at low RPM. Too small a carburetor will have a power drop, and cause the engine to run hot.

The link provided above shows a Carter spec sheet from the Carter Master Parts book for a YF intended for use on a Willys 4 cylinder 134 cubic inch engine (not suitable for Chevrolet 6); and the YF repair instructions (these are generic) and suitable for all YF to be used in conjunction with the appropriate spec sheet .

One other thing to consider: Carter used "velumoid" gaskets in the older YF units. These gaskets shrink over time. If you find a NOS YF, rebuild it with a modern kit prior to use. Be very cautious of using NOS repair kits. Check the gasket fit.

As to the quoted CFM of 250? Carter did not publish CFM ratings on any of the early YF carburetors. Some may reach this figure, many will not. Again, it depends on the individual carburetor.

Jon.

Lets see what Carbking can do with this......the carb has stamped on it H57 and then to the right of that 9645. Jethro Bodean and I can cipher and even do our guzintas but I dont think either one of us can make heads or tails of these numbers

Any help yall can lend would be much abliged.

Yall come back now, hear?

Bluebird - assuming you misread an "S" for a "5", and that you meant 964-S; then you have a aftermarket replacement for a 1937 - 1962 Chevy 216.

I would not suggest this unit for a 270. Find a Chevy dude with a 216 and sell him the unit; then locate either the original Zenith, or another carb capable of feeding your 270.

To determine your original carburetor, try this link:

http://www.thecarburetorshop.com/TRGMC.htm

Jon.

How do I go about shopping for a new Carb? What kind of flow do I need, 100, 150, 200CFM? I had the 270 completely machined recently due to a spun bearing and it is now .030 over. I dont expect that makes much difference.

I have not heard much good about the Zenith so I am a little apprehensive about going to that. Is there a good Carter site where I can find the right YF with enough flow for my 270?

Thanks for all the good information. I appreciate it!

Tom

Tom (bluebird) - Zenith made an excellent carburetor (they still do). One reason you hear little good is that they were not used on most light-duty pickups (too expensive!), so most mechanics are simply not that familiar with the carburetors. Also, parts can be a problem locally (no problem with parts using the internet).

Checked the Carter Master manual, and can find no data as to CFM on any of the YF carbs. It simply was not published. However Chevrolet used the YF on the 250 in some trucks in the 1965 to 1967 years. I believe the base will be larger than the base on your manifold.

I would give some thought to a Zenith, either original or a new replacement. It is an excellent unit, and everything fits like it was made to fit. Also, if you ever do anything for increased performance, most of the Zenith units have replaceable venturi, so a larger venturi could be installed. The Carter (or Rochester) units have fixed venturi.

Jon.